Abstract: Based on analyzing the situation of the stress concentration on the splines of the steering column, and the torsion failure testing on the streeing column, some important conclusion are obtained in this paper. The length of untouched zone near groove between the outer-splines and inner-splines can effect the load bearing capacity, and the length should be just as the diameter of transition arc of the root of splines. The load bearing capacity would be maximun when the tightening moment on the streering wheel is about 70N·m.